Invertase (EC 3.2.1.26) is found in a wide range of organisms, including bacteria, fungi, higher plants, and animals. (1). In plants, invertase is an essential enzyme that is responsible for the hydrolysis of sucrose to D-glucose and D-fructose. These hexoses provide substrate and energy for development of plants. Although considerable evidence points to the importance of invertase genes in plants,there are no reports dexcribing the isolation of genomic invertase genes in plants. We propose here to identify and characterize the structure of invertase genes, analyze the expression of these genes, and to examine the potential roles of invertases in oats. This project will be funded by NASA biology program. In our lab, invertase has been purifies from oat shoots and polyclonal antibodies raised against the deglycosylated oat invertase have been obtained (1). Recently, we have generated a partial-length cDNA (550bp) encoding oat invertase by the polymerase chain reaction (PCR). Two primers were designed for the PCR, based on two conserved motifs of invertases from prokaryoted to eukaryotes (3). This partial-length cDNA has been sequenced (3). Furthermore, we have observed that invertase mRNA show kinetic changes during the graviresponse of oat pulvini, and that the invertase mRNA level is higher in the bottom halves than that of the top halves of graviresponding pulvini (3). We have also found that three or four invertase genes may exist in oats (3). In order to study molecular mechanisms of invertase gene expression in detail, we have constructed cDNA and genomic DNA libraries. Positive clones have been isolated and are being sequenced. We would like to apply for using the GCG Swquence Analysis Software Pakage, and use our personal computer to do the following researches: (1) analysis the stucture of identified invertase genes; (2) amino acid sequences translation based on the nucleotide sequences; (3) comparison of nucleotide sequences of different invertase genes; (4) searching for homology among amino acid sequences deduced from nucleotide sequences; (5) searching for conserved regions among different invertase genes; (6) transgenic analysis of invertase genes; and (8) do other characterization of invertase genes.